Recently, as a device for medically treating a patent foramen ovale (hereinafter, referred to as PFO) which is a cardiogenic factor in strokes and migraine headaches, there has been proposed a device described in International Application Publication No. WO/2007/100067. This publication describes a PFO closing device in which an apparatus is inserted into the foramen ovale from the right atrium toward the left atrium, a foramen ovale valve is pulled so as to close the foramen ovale by a pressing device which is bent inside the left atrium, the foramen ovale valve and the atrial septum secundum are sandwiched by a pair of electrodes, and the biological tissue is fused by applying electric energy from both the electrodes.
The pressing device is constructed so that by carrying out traction of an operation wire extending from the operation unit on the hand side of the device to the distal portion thereof toward the pull-out direction at the hand side operation unit, a distal member fixed at the distal end of the operation wire is moved to the hand side (proximally) and by utilizing the moving force of this distal member, the operation wire bends the passing-through member at the distal portion of the device.
When a foreign object gets mixed inside a blood vessel, there is a fear that the foreign object is carried to the brain by the blood flow and a cerebral infarction is caused. Therefore, when pulling the operation wire in order to bend the pressing device, it is necessary to adjust the traction force such that the distal member fixed on the operation wire does not drop out by any possibility.